Modulation of higher-plant NAD(H)-dependent glutamate dehydrogenase activity in transgenic tobacco via alteration of beta subunit levels

Purnell, M. P., Skopelitis, D. S., Roubelakis-Angelakis, K. A. and Botella, Jose R. (2005) Modulation of higher-plant NAD(H)-dependent glutamate dehydrogenase activity in transgenic tobacco via alteration of beta subunit levels. Planta, 222 1: 167-180. doi:10.1007/s00425-005-1510-z


Author Purnell, M. P.
Skopelitis, D. S.
Roubelakis-Angelakis, K. A.
Botella, Jose R.
Title Modulation of higher-plant NAD(H)-dependent glutamate dehydrogenase activity in transgenic tobacco via alteration of beta subunit levels
Journal name Planta   Check publisher's open access policy
ISSN 0032-0935
Publication date 2005-09-01
Year available 2005
Sub-type Article (original research)
DOI 10.1007/s00425-005-1510-z
Open Access Status Not yet assessed
Volume 222
Issue 1
Start page 167
End page 180
Total pages 14
Editor Anastasios Melis
Dorothea Bartels
Place of publication Berlin
Publisher Springer-Verlag
Language eng
Subject C1
270402 Plant Physiology
620100 Field Crops
Abstract Glutamate dehydrogenase (GDH; EC 1.4.1.2-1.4.1.4) catalyses in vitro the reversible amination of 2-oxoglutarate to glutamate. In vascular plants the in vivo direction(s) of the GDH reaction and hence the physiological role(s) of this enzyme remain obscure. A phylogenetic analysis identified two clearly separated groups of higher-plant GDH genes encoding either the alpha- or beta-subunit of the GDH holoenzyme. To help clarify the physiological role(s) of GDH, tobacco (Nicotiana tabacum L.) was transformed with either an antisense or sense copy of a beta-subunit gene, and transgenic plants recovered with between 0.5- and 34-times normal leaf GDH activity. This large modulation of GDH activity (shown to be via alteration of beta-subunit levels) had little effect on leaf ammonium or the leaf free amino acid pool, except that a large increase in GDH activity was associated with a significant decrease in leaf Asp (similar to 51%, P=0.0045). Similarly, plant growth and development were not affected, suggesting that a large modulation of GDH beta-subunit titre does not affect plant viability under the ideal growing conditions employed. Reduction of GDH activity and protein levels in an antisense line was associated with a large increase in transcripts of a beta-subunit gene, suggesting that the reduction in beta-subunit levels might have been due to translational inhibition. In another experiment designed to detect post-translational up-regulation of GDH activity, GDH over-expressing plants were subjected to prolonged dark-stress. GDH activity increased, but this was found to be due more likely to resistance of the GDH protein to stress-induced proteolysis, rather than to post-translational up-regulation.
Keyword Ammonium Assimilation
Beta Subunit
Gene Family
Glutamate Dehydrogenase
Nitrogen Metabolism
Tobacco
Translational Inhibition
Plant Sciences
Performance Liquid-chromatography
Vitis-vinifera L
Nitrogen Assimilation
Arabidopsis-thaliana
Amino-acids
Nicotiana-plumbaginifolia
Nitrate Reductase
Synthetase Gene
Null Mutant
Zea-mays
Plant Sciences
Q-Index Code C1
Institutional Status UQ

 
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Created: Wed, 15 Aug 2007, 15:53:47 EST